System and method for providing voice communications for radio network

BACKGROUND OF THE INVENTION

00011. Field of the Invention

0002This invention pertains in general to systems and methods of providing voice communications for a radio network, and more particularly, to systems and methods of providing Voice-over-Internet-Protocol service for a radio network between a wireless communication device and an end terminal in a packet data network.

00032. Description of the Related Art

0004Global System for Mobile communications (“GSM”) has become a popular technology for digital mobile phones and a predominant system for mobile communications in Europe and numerous other countries around the world. GSM, a circuit-switched system, however, is not designed for data communications. As a result, traditional GSM system was not able to provide satisfactory services for data communications, which require high degree of accessibility, high data communication rate, and low cost. General Packet Radio Service (“GPRS”) was proposed to resolve the problems of providing data communications in a GSM network. The GPRS operates to provide data packet exchange services under the existing GSM networks and systems. The core network of the GPRS has become part of the second generation of the Time-Division-Multiple-Access (“TDMA”) cellular system, or the so-called Interim Standard-136 (“IS-136”) TDMA system. IS-136 is a North American digital mobile telephony standard based on TDMA technology. It is a TDMA specification that is used to create in a fully digital second generation system and is backward compatible with analog Advanced Mobile Phone System (“AMPS”). It is expected that the GPRS will be further developed as the core network of the third-generation mobile phone system.

0005The demand of providing voice communications over the Internet, the so-called Voice-over-Internet-Protocol (“VoIP”) service, has been greatly increased in the last several years. Gardell et al. described, in U.S. Pat. No. 6,128,304, a method and apparatus for providing traditional telecommunications services capabilities in a packet-based computer network. Their invention is directed to the application of such services in an H.323-based system but did not apply to wireless systems.

0006Combining VoIP service with mobile phone systems is one of the important goals of current development efforts. Most recent developments on VoIP service involved providing the service in Internet-based networks, or between an end terminal in the Internet and a traditional telephone terminal. Other GPRS developments focused on the control and efficiency of data packet transmissions. Dahlin et al. proposed, in U.S. Pat. No. 6,122,263, a scheme for providing Internet access for cellular networks, which receives and analyzes packets from a packet-switched fixed network. Their invention enabled routing of wideband traffic from a packet-switched fixed network over a radio interface to a mobile terminal, but did not provide VoIP service for a GPRS network.

0007<figref idref="DRAWINGS">FIG. 1</figref> is a block diagram illustrating the main structure of a known GPRS network <b>10</b>. GPRS network <b>10</b> includes several elements of a traditional GSM network, including a Base Transceiver Station (“BTS”) <b>12</b>, a Base Station Controller (“BSC”) <b>14</b>, a Mobile Switching Center (“MSC”) <b>16</b>, a Home Location Register (“HLR”) <b>18</b>, and a Visitor Location Register (“VLR”) <b>20</b>. In addition to traditional GSM network elements, GPRS network <b>10</b> further includes a Serving GPRS Support Node (“SGSN”) <b>22</b> and a Gateway GPRS Support Node (“GGSN”) <b>24</b>. A wireless communication device <b>30</b>, such as a GSM mobile phone, communicates with GPRS network <b>10</b> through BTS <b>12</b>. SGSN <b>22</b> and GGSN <b>24</b>, through the channeling of other devices, transmits data packets between the wireless communication device <b>30</b> and a data network <b>32</b>, such as a Public Switched Data Network (“PSDN”), or namely, the Internet.

0008BSC <b>14</b> includes a base station Packet Control Unit (“PCU”) <b>14</b><i>b </i>in order to communicate with SGSN <b>22</b>. As a result, BSC <b>14</b> directs circuit-switched voice signals to MSC <b>16</b> and directs packet-switched data to SGSN <b>22</b> through the base station PCU <b>14</b><i>b</i>. MSC <b>16</b> then directs voice signals of ordinary phone calls to a Publicly Switched Telephone Network (“PSTN”). Traditionally, one BSC <b>14</b> can communicate with only one SGSN <b>22</b>. GGSN <b>24</b>, which communicates with SGSN <b>22</b>, communicates with external data network <b>32</b>. SGSN <b>22</b> and GGSN <b>24</b> are responsible for communicating with HLR <b>18</b> and VLR <b>20</b> in order to locate a wireless communication device, such as a mobile phone.

0009Therefore, wireless communication device <b>30</b> communicates with the Internet in data packet form through the operation of BTS <b>12</b>, BSC <b>14</b>, SGSN <b>22</b>, and GGSN <b>24</b>. A traditional GPRS network does not support VoIP services because wireless communication device <b>30</b> has no capability of processing H.323 packets. Further, no specific schemes are designed to register mobile phones to data network <b>32</b> and to allow mobile phones to initiate a phone call to or receive a phone call from an end terminal in data network <b>32</b>.

0010To resolve the problem, one of the proposed specifications and studies for third generation mobile systems, 3G TR 21.978, provides a VoIP scheme for a GPRS network. 3G TR 21.978 is a document developed within the third-generation partnership project. The document contains a feasibility report of the proposed VoIP scheme that enables VoIP calls between third-generation (3G) terminals or between a 3G terminal and legacy network terminal, such as second-generation (2G) mobile, Integrated Service Digital Network (“ISDN”) or PSTN. The proposed scheme implements an “in-band signaling” concept that transmits signals and voice information with the same Packet-Data-Protocol (“PDP”) concept. The scheme requires deactivation of a PDP context previously activated after a mobile phone completes a registration procedure to a H.323 network. Therefore, the mobile phone has to reactivate the PDP context each time a user makes or receives a call. The time needed for establishing a phone conversation channel is increased by the repetition of deactivation and reactivation processes. Further, the scheme proposed in 3G TR 21.978 requires modification of a standard H.323 interface, such as a H.323 gatekeeper, in order to implement the proposed scheme. The required modification limits the application of the proposed scheme.

SUMMARY OF THE INVENTION

0011Accordingly, the present invention is directed to systems and methods for providing Voice-over-Internet-Protocol service for radio networks that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.

0012Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the systems and methods particularly pointed out in the written description and claims hereof, as well as the appended drawings.

0013To achieve these and other advantages, and in accordance with the purpose of the invention as embodied and broadly described, the present invention provides systems for providing voice communications between an end terminal in a packet data network and a wireless communication device. In one embodiment of the present invention, a system for providing voice communications includes a packet communication supporting subsystem, a base station subsystem, and a Voice-over-Internet-Protocol Mobile Switching Center (“VMSC”). The packet communication supporting subsystem communicates with the packet data network and also operates to locate the wireless communication device. The base station subsystem communicates with the wireless communication device, and also with the packet data network through the packet communication supporting subsystem in the form of data packets. The Voice-over-Internet-Protocol Mobile Switching Center communicates with the packet communication supporting subsystem through a packet-switched network and communicates with the base station subsystem through a circuit-switched network.

0014The present invention also provides registration, call-making, call-releasing, and call-receiving methods for a wireless communication device in order to provide voice communications between the wireless communication device and an end terminal in a packet data network.

0015One embodiment of the registration method of the present invention includes performing a location update of the wireless communication device, authenticating the identity of the wireless communication device, and performing a ciphering procedure for the wireless communication device. After the ciphering procedure, the registration method further includes notifying a Voice-over-Internet-Protocol Mobile Switching Center (“VMSC”) of the registration of the wireless communication device, activating the communication between the VMSC and the packet data network, performing a registration of the wireless communication device to the packet data network, and notifying the wireless communication device of the completion of location update. The VMSC in the registration method of the present invention communicates with the wireless communication device through a circuit-switched network and with the end terminal through a packet-switched network.

0016In one embodiment of the present invention, the activation of the communication between the VMSC and the packet data network in the registration method may include initiating a new Packet Data Protocol (“PDP”) context by the VMSC, establishing a record for the wireless communication device by a Gateway GPRS Support Node (“GGSN”), and enabling an Internet-Protocol (“IP”) communication between a gatekeeper (“GK”) and the VMSC. The GGSN communicates with the packet data network through the GK and with the VMSC through a supporting Serving GPRS Support Node (“SGSN”). In addition, the registration of the wireless communication device to the packet data network may include initiating the registration and notifying the GK of the packet data network by the VMSC with an alias address and a transport address, creating a record by the GK for the mobile phone containing corresponding information of a mobile phone number to an IP address, and notifying the VMSC of the completion of the registration by the GK. The VMSC then establishes Mobility Management (“MM”) and PDP context and stores the context in a mobile phone record of the VMSC.

0017The call-making method of the present invention includes performing channel assignment, authentication, and ciphering setup procedures for the wireless communication device. The call-making method also includes performing a call setup procedure for the wireless communication device, establishing a voice communication channel between a Voice-over-Internet Protocol Mobile Switching Center (“VMSC”) and the packet data network, alerting the end terminal and the wireless communication device, and performing a PDP context activation for voice transmission. Finally, the end terminal and the wireless communication device are connected through the VMSC. The VMSC communicates with the wireless communication device through a circuit-switched network and communicates with the end terminal through a packet-switched network.

0018In one embodiment of the call-making method of the present invention, the step of establishing the voice communication channel includes providing the Internet-Protocol (“IP”) address of the end terminal to the VMSC by a gatekeeper (“GK”) of the packet data network and communicating with the end terminal by the VMSC to exchange setup and call-proceeding signals between the VMSC and the end terminal. The step of establishing the voice communication channel also includes transmitting Registration, Admission and Status (“RAS”) Admission Request (“ARQ”) signals to the GK and requesting communications by the end terminal.

0019The call-releasing method of the present invention includes disconnecting voice communications by the wireless communication device, sending a release signal to the end terminal by a VMSC, exchanging disengage requests between the VMSC and the end terminal, and performing a deactivation procedure. The VMSC communicates with the wireless communication device through a circuit-switched network and communicates with the end terminal through a packet-switched network.

0020The call-receiving method of the present invention includes establishing a voice communication channel between a VMSC and the end terminal, paging the wireless communication device, and performing channel assignment, authentication, and ciphering setup procedures for the wireless communication device upon receiving a response from the wireless communication device. The call-receiving method further includes performing a call setup procedure for the wireless communication device, alerting the wireless communication device and alerting the end terminal in the packet data network, and connecting the end terminal and the wireless communication device through the VMSC. Finally, the VMSC activates voice communications for the wireless communication device. The VMSC in the call-receiving method communicates with the wireless communication device through a circuit-switched network and communicates with the end terminal through a packet-switched network. In one embodiment of the call-receiving method of the present invention, the step of establishing the voice communication channel includes performing Registration, Admission and Status (“RAS”) admission request and setup procedures, sending a setup signal to the VMSC by the end terminal, the VMSC responds to the end terminal with a call proceeding signal and exchanges RAS and ARQ signals with the GK. More particularly, in the RAS admission request and setup procedures, the end terminal transmits a RAS admission request signal to a gatekeeper (“GK”) of the packet data network, which contains the identity of the wireless communication device, and the GK responds to the end terminal with a RAS admission confirmation signal.

0021It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

0022The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the objects, advantages, and principles of the invention.

0023In the drawings:

0024<figref idref="DRAWINGS">FIG. 1</figref> is a block diagram illustrating the main structure of a known GPRS network.

0025<figref idref="DRAWINGS">FIG. 2</figref> a block diagram illustrating one embodiment of the system of the present invention for providing voice communications between a wireless communication device and an end terminal in a packet data network;

0026<figref idref="DRAWINGS">FIG. 3</figref> a block diagram illustrating one embodiment of the present invention of the interfaces between a VMSC and other elements in a GSM/GPRS network;

0027<figref idref="DRAWINGS">FIG. 4</figref> a block diagram illustrating the communication between a H.323 terminal and a GSM mobile phone in one embodiment of the present invention;

0028<figref idref="DRAWINGS">FIG. 5</figref> is a general flow diagram for implementing one embodiment of the registration methods of the present invention;

0029<figref idref="DRAWINGS">FIG. 6</figref> is a general flow diagram for implementing one embodiment of the call-making methods of the present invention;

0030<figref idref="DRAWINGS">FIG. 7</figref> is a general flow diagram for implementing one embodiment of the call-releasing methods of the present invention; and

0031<figref idref="DRAWINGS">FIG. 8</figref> is a general flow diagram for implementing one embodiment of the call-receiving methods of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

0032Major terms used in the detailed description of the present invention are provided below:

0033<tables id="TABLE-US-00001" num="00001"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="1" colwidth="28pt" align="left" /><colspec colname="2" colwidth="189pt" align="left" /><thead><row><entry namest="1" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry>AMPS</entry><entry>Advanced Mobile Phone System</entry></row><row><entry>ARQ</entry><entry>Admission Request</entry></row><row><entry>BSC</entry><entry>Base Station Controller</entry></row><row><entry>BTS</entry><entry>Base Transceiver Station</entry></row><row><entry>DCFs</entry><entry>Disengage Confirmations</entry></row><row><entry>DRQs</entry><entry>Disengage Requests</entry></row><row><entry>GGSN</entry><entry>Gateway GPRS Support Node</entry></row><row><entry>GK</entry><entry>GateKeeper</entry></row><row><entry>GPRS</entry><entry>General Packet Radio Service</entry></row><row><entry>GSM</entry><entry>Global Systems for Mobile communication</entry></row><row><entry>GTP</entry><entry>GPRS Tunneling Protocol</entry></row><row><entry>H.323</entry><entry>An International-Telecommunications-Union (“ITU”) standard</entry></row><row><entry /><entry>for realtime, interactive voice and videoconferencing over</entry></row><row><entry /><entry>Local Area Networks (“LANs”) and the Internet. Widely used</entry></row><row><entry /><entry>for IP telephony, it allows any combination of voice, video and</entry></row><row><entry /><entry>data to be transported.</entry></row><row><entry>H.225</entry><entry>a call signaling scheme that is used to set up connections</entry></row><row><entry /><entry>between two points, such as terminals and gateways, over</entry></row><row><entry /><entry>which the real-time data can be transported.</entry></row><row><entry>HLR</entry><entry>Home Location Register</entry></row><row><entry>IS-136</entry><entry>Interim Standard-136: It is a North American digital mobile</entry></row><row><entry /><entry>telephony standard based on TDMA technology. It is a TDMA</entry></row><row><entry /><entry>specification that is used to create in a fully digital second</entry></row><row><entry /><entry>generation system and is backward compatible with analog</entry></row><row><entry /><entry>AMPS.</entry></row><row><entry>IMSI</entry><entry>International Mobile Subscriber Identity</entry></row><row><entry>IP</entry><entry>Internet Protocol</entry></row><row><entry>ISDN</entry><entry>Integrated Service Digital Network</entry></row><row><entry>ISUP</entry><entry>Integrated-service-digital-network User Part</entry></row><row><entry>MM</entry><entry>Mobility Management</entry></row><row><entry>MSC</entry><entry>Mobile Switching Center</entry></row><row><entry>PCU</entry><entry>Packet Control Unit</entry></row><row><entry>PDN</entry><entry>Packet Data Network</entry></row><row><entry>PDP</entry><entry>Packet Data Protocol</entry></row><row><entry>PSDN</entry><entry>Public Switched Data Network</entry></row><row><entry>PSTN</entry><entry>Public Switched Telephone Network</entry></row><row><entry>QoS</entry><entry>Quality of Service</entry></row><row><entry>RAS</entry><entry>Registration, Admission and Status</entry></row><row><entry>SGSN</entry><entry>Serving GPRS Support Node</entry></row><row><entry>SS7</entry><entry>Common Channel Signaling System #7: It is a global</entry></row><row><entry /><entry>telecommunications standard for the signaling system that</entry></row><row><entry /><entry>allows the various components of a telephone network to</entry></row><row><entry /><entry>exchange information and connect calls.</entry></row><row><entry>TCP/IP</entry><entry>Transmission Control Protocol/Internet Protocol</entry></row><row><entry>TDMA</entry><entry>Time-Division-Multiple-Access</entry></row><row><entry>TMSI</entry><entry>Temporary Mobile Subscriber Identity</entry></row><row><entry>VLR</entry><entry>Visitor Location Registor</entry></row><row><entry>VMSC</entry><entry>Voice-over-Internet-Protocol Mobile Switching Center</entry></row><row><entry>VoIP</entry><entry>Voice over Internet Protocol</entry></row><row><entry namest="1" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0034The present invention provides systems and methods of providing voice communications for radio networks. Preferably, the systems and methods of the present invention provide VoIP service for a radio network, such as a General Packet Radio Service (“GPRS”) network, that communicates between a wireless communication device and an end terminal in a Packet Data Network (“PDN”).

0035The systems and methods of the present invention provide a Voice-over-Internet-Protocol Mobile Switching Center (“VMSC”) that communicates with the wireless communication device through a circuit-switched network and communicates with the packet data network with a packet-switched network. In the embodiments for implementing the present invention in a GPRS network, the VMSC in the present invention transforms voice signals from a circuit-switched network, such as a Global-Systems-for-Mobile-Communication (“GSM”) network, to voice packets for a packet-switched network, such as a GPRS network. The systems and methods of the present invention may operate under the standard H.323, GPRS, and GSM protocol and erase the need of modifying the operation of a traditional packet-switched GPRS and H.323 networks. The systems and methods for providing VoIP service in the present invention enable standard GSM and GPRS mobile phones to receive VoIP service and eliminate the need for equipping mobile phones with H.323 communicating capability.

0000Systems for Providing Voice Communications

0036<figref idref="DRAWINGS">FIG. 2</figref> is a block diagram illustrating one embodiment of the system of the present invention for providing voice communications between a packet data network <b>50</b> and a wireless communication device <b>52</b>. As an example, packet data network <b>50</b> may be a Public Switched Data Network (“PSDN”), such as the Internet or a network that implements H.323 standard; wireless communication device <b>52</b> may be a mobile phone. In one embodiment, a network <b>100</b> communicating between packet data network <b>50</b> and wireless communication device <b>52</b> may be a radio network implementing General Packet Radio Service.

0037The system of the present invention includes a packet communication supporting subsystem <b>54</b>, a base station subsystem <b>56</b>, and a VMSC <b>58</b>. Packet communication supporting subsystem <b>54</b> communicates with the packet data network <b>50</b>, base station subsystem <b>56</b>, and VMSC <b>58</b>. In general, packet communication supporting subsystem <b>54</b> also operates to locate the wireless communication device <b>52</b> by communicating with other databases in network <b>100</b>. In one embodiment implementing GPRS, packet communication supporting subsystem <b>54</b> includes a Gateway GPRS Support Node (“GGSN”) <b>54</b><i>a </i>and a Serving GPRS Support Node (“SGSN”) <b>54</b><i>b</i>. GGSN <b>54</b><i>a </i>communicates with packet data network <b>50</b> and SGSN <b>54</b><i>b </i>communicates with GGSN <b>54</b><i>a </i>and VMSC <b>58</b>.

0038Network <b>100</b> may also include two databases, a Home Location Register (“HLR”) <b>60</b> and a Visitor Location Registor (“VLR”) <b>62</b>, which are traditional elements in a GSM network. In one embodiment implementing a GPRS and GSM network, GGSN <b>54</b><i>a </i>and SGSN <b>54</b><i>b </i>communicates with HLR <b>60</b> and VLR <b>62</b> to locate wireless communication device <b>52</b>. In addition, the system of the present invention may include a GateKeeper (“GK”) <b>50</b><i>b </i>in packet data network <b>50</b>, which operates as a gatekeeper for a H.323 network in part to transform Internet-Protocol (“IP”) addresses. Therefore, GGSN <b>54</b><i>a </i>may communicate with packet data network <b>50</b> through GK <b>50</b><i>b</i>, as illustrated in <figref idref="DRAWINGS">FIG. 2</figref>.

0039Base station subsystem <b>56</b> communicates with wireless communication device <b>52</b> and packet communication supporting subsystem <b>54</b>, or more specifically, SGSN <b>54</b><i>b </i>for an embodiment implementing GPRS. Packet communication supporting subsystem <b>54</b> communicates data packets between base station subsystem <b>56</b> and packet data network <b>50</b>. In one embodiment, base station subsystem <b>56</b> includes a Base Station Controller (“BSC”) <b>56</b><i>a </i>and a Base Transceiver Station (“BTS”) <b>56</b><i>c</i>. BSC <b>56</b><i>a </i>communicates with packet communication supporting subsystem <b>54</b> through a base station Packet Control Unit (“PCU”) <b>56</b><i>b</i>; BTS <b>56</b><i>c </i>communicates with wireless communication device <b>52</b> by radio communication.

0040VMSC <b>58</b> communicates with packet communication supporting subsystem <b>54</b> through a packet-switched network, such as a GPRS network, and communicates with base station subsystem <b>56</b> through a circuit-switched network, such as a GSM network. More specifically, VMSC <b>58</b> receives voice signals from base station subsystem <b>56</b> and then generates and transmits voice packets to packet communication supporting subsystem <b>54</b>. VMSC <b>58</b> also receives voice packets from packet communication supporting subsystem <b>54</b> and transmits voice signals to base station subsystem <b>56</b>. The voice packets are transmittable through a GPRS network. In one embodiment, VMSC <b>58</b> includes a vocoder <b>58</b><i>a </i>and a Packet Control Unit (“PCU”) <b>58</b><i>b </i>communicating with the vocoder <b>58</b><i>a</i>. Further, vocoder <b>58</b><i>a </i>communicates through a circuit-switched network to receive voice signals from, or submit voice signals to, the base station subsystem <b>56</b>, and PCU <b>58</b><i>b </i>communicates through a packet-switched network to receive voice packets from, or submit voice packets to, the packet communication supporting subsystem <b>54</b>. Therefore, vocoder <b>58</b><i>a </i>and PCU <b>58</b><i>b </i>operate together to process at least two forms of voice information, voice signals and voice packets. More specifically, vocoder <b>58</b><i>a </i>compresses a digitized data stream into compressed data and PCU <b>58</b><i>b </i>outputs the voice information in packet form; PCU <b>58</b><i>b </i>also receives voice information in packet forms and vocoder <b>58</b><i>a </i>decompresses the compressed data into a digitized data stream. In one embodiment of the present invention, the vocoder <b>58</b><i>a </i>may employ a high-speed digital signal processor with supporting memory devices.

0041Therefore, as illustrated by <figref idref="DRAWINGS">FIG. 2</figref>, in one embodiment of implementing GPRS and GSM, the system of the present invention, which operates between wireless communication device <b>52</b> and packet data network <b>50</b>, may include BTS <b>56</b><i>c</i>, BSC <b>56</b><i>a</i>, VMSC <b>58</b>, SGSN <b>54</b><i>b</i>, GGSN <b>54</b><i>a</i>, and GK <b>50</b><i>b</i>. VMSC <b>58</b> communicates with SGSN <b>54</b><i>b </i>with a Gb interface in GPRS network, in the form of voice packets, or more specifically, VoIP packets or GPRS packets. As a result, wireless communication device <b>52</b> communicates ordinary non-voice packets with packet data network <b>50</b> through the path of (1)⇄(2)⇄(3)⇄(4) as shown in <figref idref="DRAWINGS">FIG. 2</figref>, which includes BTS <b>56</b><i>c</i>, BSC<b>56</b><i>a</i>, SGSN <b>54</b><i>b</i>, and GGSN<b>54</b><i>a</i>. In contrast, wireless communication device <b>52</b> communicates with packet data network <b>50</b>, for the purpose of providing VoIP services, through the path of (1)⇄(2)⇄(5)⇄(6)⇄(4), as shown in <figref idref="DRAWINGS">FIG. 2</figref>, which includes BTS <b>56</b><i>c</i>, BSC<b>56</b><i>a</i>, VMSC<b>58</b>, SGSN <b>54</b><i>b</i>, and GGSN<b>54</b><i>a</i>. For VoIP services, the communications through path (6) and path (4), or the communicating paths between VMSC <b>58</b> and SGSN <b>54</b><i>b </i>and between SGSN <b>54</b><i>b </i>and GGSN <b>54</b><i>a</i>, are in a voice-data packet form. Path (1)⇄(2)⇄(5), which includes the communicating paths between wireless communication device <b>52</b> and BTS <b>56</b><i>a </i>and between BSC <b>56</b><i>a </i>and VMSC <b>58</b>, is a circuit-switched path that communicates in the same way as an ordinary GSM network. Under the system of the present invention, standard GSM and GPRS mobile phones are able to make and receive VoIP calls in the same way as making and receiving ordinary phone calls.

0042In one embodiment of the present invention, VMSC <b>58</b> may be used to replace a Mobile Switching Center (“MSC”) in a GSM network. VMSC <b>58</b> operates as a softswitch having the function of a router and is therefore simpler than a traditional MSC. <figref idref="DRAWINGS">FIG. 3</figref> is a block diagram illustrating the interfaces between VMSC <b>58</b> and other elements in a GSM/GPRS network in the present invention. VMSC <b>58</b> employs the same signal interface as an ordinary MSC, which means VMSC <b>58</b> communicates with BSC <b>56</b><i>a</i>, VLR <b>62</b>, and a Publicly Switched Telephone Network (“PSTN”) <b>64</b> respectively through interface A, interface B, and the Integrated-Service-Digital-Network User Part (“ISUP”) of Signaling System No.7 (“SS7”). VMSC <b>58</b>, however, communicates with SGSN <b>54</b><i>b </i>through a Gb interface of a GPRS network. A traditional MSC communicates voice signals of ordinary phone calls through a circuit-switched network, such as a telephone trunk. In contrast, VMSC <b>58</b> communicates VoIP packets through a packet-switched network, such as a GPRS network.

0043As an illustration of one embodiment of the present invention, each mobile phone that submits voice signals through VMSC <b>58</b> will be given an IP address. In a GPRS network, the IP address of a mobile phone can be assigned statically or dynamically. A standard GSM mobile phone, however, cannot be assigned with an IP address. Therefore, for the implementation of the present invention in a GPRS network, VMSC <b>58</b> operates to assign an IP address through a GPRS Packet-Data-Protocol (“PDP”) Context Activation process.

0044In one embodiment, VMSC <b>58</b> contains a mobile phone table that stores information related to each mobile phone, such as MM and PDP context information, which includes Temporary Mobile Subscriber Identity (“TMSI”), International Mobile Subscriber Identity (“IMSI”), and certain Quality-of-Service (“QoS”) related information. This kind of information is basically similar to what is stored on each mobile phone. In one embodiment, the system of the present invention employs H.323 protocol to transmits voice information and VMSC <b>58</b> therefore functions in part as a H.323 terminal.

0045<figref idref="DRAWINGS">FIG. 4</figref> is a block diagram illustrating the communication between a H.323 terminal <b>66</b> in a VoIP network <b>68</b> and a GSM mobile phone <b>70</b> in one embodiment of the present invention. As illustrated in the diagram, the system of this embodiment includes several communication channels: C<b>1</b> between H.323 terminal <b>66</b> and GK <b>50</b><i>b</i>, C<b>2</b> between GK <b>50</b><i>b </i>and GGSN <b>54</b><i>a</i>, C<b>3</b> between GGSN <b>54</b><i>a </i>and SGSN <b>54</b><i>b</i>, C<b>4</b> between SGSN <b>54</b><i>b </i>and VMSC <b>58</b>, C<b>5</b> between VMSC <b>58</b> and BSC <b>56</b><i>a</i>, C<b>6</b> between BSC <b>56</b><i>a </i>and BTS <b>56</b><i>c</i>, C<b>7</b> between BTS <b>56</b><i>c </i>and GSM mobile phone <b>70</b>, C<b>8</b> between H.323 terminal <b>66</b> and GGSN <b>54</b><i>a</i>, C<b>9</b> between VMSC <b>58</b> and VLR <b>62</b>, and C<b>10</b> between VLR <b>62</b> and HLR <b>60</b>. Communication channels C<b>1</b>, C<b>2</b>, and C<b>8</b> employ Transmission Control Protocol/Internet Protocol (“TCP/IP”); communication channels C<b>3</b> and C<b>4</b> respectively employ GPRS tunneling Protocol (“GTP”) and Gb Protocol; communication channels C<b>5</b>, C<b>6</b>, C<b>7</b>, C<b>9</b>, and C<b>10</b> employ standard GSM protocol. More specifically, H.323 protocol, which is a TCP/IP-based protocol, is employed in communications between VMSC <b>58</b> and a H.323 network <b>68</b> and H.323 protocol is based on TCP/IP.

0000Registration Methods

0046The present invention also provides registration methods for providing voice communications between a wireless communication device and an end terminal in a packet data network. <figref idref="DRAWINGS">FIG. 5</figref> is a general flow diagram for implementing one embodiment of the registration methods of the present invention. The diagram also illustrates the network elements that are involved in each step. Once a wireless communication device, such as a mobile phone, is turned on, a location update procedure of the wireless communication device is performed at step <b>1</b>.<b>1</b>. In one embodiment implementing GPRS and GSM, a standard GSM location update procedure is performed. The identity of the wireless communication device is then authenticated in step <b>1</b>.<b>2</b>, for example, by a standard GSM authentication procedure. For a network system including two databases of a VLR and a HLR, the location update procedure in step <b>1</b>.<b>1</b> further includes a sub-step of performing another standard GSM location procedure wherein the VLR notifies location update information of a mobile phone to the HLR, and, upon receiving the location update information, the HLR submits the ordering information regarding the mobile phone to the VLR at step <b>1</b>.<b>3</b>.

0047After the location update and authentication procedures, a ciphering procedure for the wireless communication device, such as a standard GSM ciphering procedure, is then performed at step <b>1</b>.<b>4</b>. A VMSC is then notified of the registration of the wireless communication device, preferably including the completion of the location update operation, at step <b>1</b>.<b>5</b>. In this embodiment, the VMSC communicates with the wireless communication device through a circuit-switched network and communicates with the end terminal through a packet-switched network. After acknowledging the registration by the VMSC, communication between the VMSC and the packet data network is activated at step <b>1</b>.<b>6</b>. In one embodiment implementing GPRS, the activation procedure involves several steps of standard GPRS attach and PDP context activation. First, the VMSC initiates a GPRS attach with a SGSN. According to a GPRS PDP Context Activation procedure, the VMSC, on behalf of a GPRS mobile phone, then initiates a new PDP context. During the initiation, a GGSN employs the IMSI of a mobile phone to obtain some information in a HLR, such as an IP address, which may be a dynamic one. The GGSN further establishes a record for the mobile phone, including information such as IMSI, IP address, QoS information, and SGSN address. At this moment, an IP session of the VMSC has been established and the VMSC therefore is able to communicate in Internet Protocol with an external H.323 network, preferably through a gatekeeper.

0048After activation step <b>1</b>.<b>6</b>, the registration of the wireless communication device to the packet data network is performed at step <b>1</b>.<b>7</b>. In one particular embodiment using a H.323 packet data network, H.323 registration is performed. For H.323 registration, the VMSC initiates H.323 registration and notifies the GK in the H.323 network of the corresponding information of an alias address to a transport address. Upon receiving the registration request of a mobile phone, the GK creates a record regarding the mobile phone that contains the corresponding information of a mobile phone number to an IP address. The GK then notifies the VMSC of the completion of H.323 registration. Upon receiving the notification, the VMSC establishes MM and PDP context and stores the context in the mobile phone record of the VMSC. The VMSC notifies the wireless communication device of a location update operation at step <b>1</b>.<b>8</b>. In one embodiment, the VMSC notifies a mobile phone that a location update request has been accepted. Registration is therefore completed.

0000Call-Making Methods

0049The present invention also provides call-making methods for a wireless communication device to activate its voice communications with an end terminal in a packet data network. <figref idref="DRAWINGS">FIG. 6</figref> is a general flow diagram for implementing one embodiment of the call-making methods of the present invention. The diagram also illustrates the network elements that are involved in each step. Channel assignment, authentication, and ciphering setup procedures for the wireless communication device, such as a mobile phone, are performed at step <b>2</b>.<b>1</b>. A call setup procedure for the wireless communication device, such as a standard GSM call setup procedure, is then performed at step <b>2</b>.<b>2</b>. In one embodiment implementing GPRS and GSM, the mobile phone, through a dialing request, sends a “Um-Setup” signal to a BSC. The BSC then sends the signal to a VMSC, preferably through GSM Abis interface and A interface. In another embodiments of the present invention, the dialing request and its content are sent to the VMSC and VMSC inquires a VLR to confirm if the requested service of making a phone call is permissible for a particular mobile phone. Upon receiving confirmation of allowance from the VLR, the VMSC checks the PDP context record and determines the routing path of packages according to the GPRS Tunnel ID and GGSN number of the mobile phone.

0050A voice communication channel is established between the VMSC and the packet data network at step <b>2</b>.<b>3</b>. The VMSC in the present invention communicates with the wireless communication device through a circuit-switched network and communicates with the end terminal through a packet-switched network. One embodiment of the present invention employs standard H.225 Registration, Admission and Status (“RAS”) admission request procedure through which a GK provided the VMSC with the IP address of the end terminal. As an illustrative example, the signal may be transmitted through a path of C<b>4</b>⇄C<b>3</b>⇄C<b>2</b> as shown in <figref idref="DRAWINGS">FIG. 4</figref>. Upon receiving a responding signal from the GK, the VMSC communicates with the end terminal through the GGSN to exchange Q.931 setup and call-proceeding signals between the VMSC and the end terminal in order to establish a voice-communication channel. The block diagram in <figref idref="DRAWINGS">FIG. 4</figref> illustrates one embodiment of the voice-communication channel that provides a signal path C<b>4</b>⇄C<b>3</b>⇄C<b>8</b> for the communication between VMSC <b>58</b> and a H.323 terminal <b>66</b>. The terminal may further transmit RAS Admission Request (“ARQ”) signals to GK <b>50</b><i>b </i>and request communications, following path C<b>1</b> as shown in <figref idref="DRAWINGS">FIG. 4</figref>.

0051Once the voice communication channel is established between the VMSC and the packet data network at step <b>2</b>.<b>3</b>, the end terminal in the packet data network and the wireless communication device, such as a mobile phone are alerted at step <b>2</b>.<b>4</b>. In one embodiment, when a communication request of the end terminal, such as a H.323 terminal, is accepted by the GK, the end terminal itself generates alerting sounds and notifies the mobile phone through standard Q.931 alerting and GSM alerting signals. Upon receiving the alerting signals, the mobile phone generates alerting sounds. The end terminal and the wireless communication device are therefore connected through the VMSC at step <b>2</b>.<b>5</b>. Preferably, the H.323 receiving terminal generates a Q.931 connect signal and transmits it to the VMSC; the VMSC sends the signal to the mobile phone sequentially through GSM-A, Abis, and Um interfaces, as shown in <figref idref="DRAWINGS">FIG. 4</figref>, respectively for channels C<b>5</b>, C<b>6</b>, and C<b>7</b>. In one embodiment, the VMSC initiates a PDP context for the mobile phone for voice communications by performing standard GPRS PDP context activation procedure at step <b>2</b>.<b>6</b>. A PDP context activation procedure is performed to create a voice PDP context. The users of the mobile phone and the H.323 terminal are able to proceed with their conversation through the communication of the VMSC, as illustrated in <figref idref="DRAWINGS">FIG. 6</figref>.

0000Call-Releasing Methods

0052The present invention further provides call-releasing methods for terminating voice communications between a wireless communication device and an end terminal in a packet data network. <figref idref="DRAWINGS">FIG. 7</figref> is a general flow diagram for implementing one embodiment of the call-releasing methods of the present invention. The diagram also illustrates the network elements that are involved in each step. Disconnecting and release procedures are performed at step <b>3</b>.<b>1</b>. In one embodiment, the voice communications provided between the wireless communication device, such as a mobile phone, and the end terminal, such as a H.323 terminal, are disconnected by the mobile phone. When a user finish conversation by “hanging up” the mobile phone, the mobile phone sends a disconnecting signal. The disconnecting signal was transmitted to a VMSC, usually through a BTS and a BSC. The VMSC in the present invention communicates with the wireless communication device through a circuit-switched network and communicates with the end terminal through a packet-switched network. The VMSC then sends a release signal. In one embodiment applying the present invention to voice communications between a mobile phone in a GPRS network and a H.323 terminal, the VMSC sends a Q.931 release complete signal to the H.323 terminal in order to terminate the conversation.

0053A disengage request procedure is performed at step <b>3</b>.<b>2</b>, preferably by exchanging disengage requests between the VMSC and the end terminal. In one embodiment, both the VMSC and the H.323 terminal exchange RAS Disengage Requests (“DRQs”) and RAS Disengage Confirmations (“DCFs”) with a GK to notify the GK that the conversation has been terminated. The GK then obtains necessary records regarding this particular phone call for determining appropriate service charges. Finally, a deactivation procedure is performed as step <b>3</b>.<b>3</b>. In one of the preferred embodiments of the present invention, a standard GPRS PDP context deactivation procedure is performed to deactivate the voice PDP context.

0000Call-Receiving Methods

0054Additionally, the present invention provides call-receiving methods for a wireless communication device to receive voice communications initiated by an end terminal in a packet data network. <figref idref="DRAWINGS">FIG. 8</figref> is a general flow diagram for implementing one embodiment of the call-receiving method of the present invention. The diagram also illustrates the network elements involved in each step. A voice communication channel is established between a VMSC and the end terminal at step <b>4</b>.<b>1</b>.

0055In one embodiment, standard H.225 RAS admission request and Q.931 setup procedures are performed. The end terminal, such as a H.323 terminal, transmits a H.225 RAS admission request signal to a GK of the packet data network, which contains the identity of the wireless communication device, such as the phone number of a mobile phone. The GK is able to find the corresponding IP address according to an IP transformation table and responds to the H.323 terminal with an H.225 RAS admission confirmation signal. The H.323 terminal sends, preferably through a GGSN, a Q.931 setup signal to a VMSC in order to establish a voice communication channel. The VMSC in the present invention communicates with the wireless communication device through a circuit-switched network and communicates with the end terminal through a packet-switched network. Upon receiving a setup signal, the GGSN obtains the PDP context of the identified wireless communication device, such as a mobile phone, according to the IP address identified by a packet received from the H.323 terminal. The GGSN then obtains the GPRS Tunnel ID and SGSN address of the mobile phone from the PDP context and sends the packet to the VMSC. Upon receiving the Q.931 signal, the VMSC responds to the H.323 terminal with a Q.931 call proceeding signal. The VMSC and GK exchange RAS ARQ and Admission Confirmation (“ACF”) signals with each other. The VMSC then sends a communication request, in a similar way as illustrated for step <b>2</b>.<b>3</b>, as shown in <figref idref="DRAWINGS">FIG. 6</figref>.

0056After the voice communication channel is established at step <b>4</b>.<b>1</b>, the VMSC pages the wireless communication device at step <b>4</b>.<b>2</b>, for example, by performing a standard GSM paging procedure. Upon receiving a response from the wireless communication device by the VMSC, channel assignment, authentication, and ciphering setup procedures for the wireless communication device are performed at step <b>4</b>.<b>3</b>. In one embodiment implementing GSM and GPRS, the VMSC and a VLR in a GSM/GPRS network operate together to perform standard GSM channel assignment, authentication, and ciphering setup procedures. A call setup procedure for the wireless communication device is performed at step <b>4</b>.<b>4</b>. In one embodiment, the VMSC performs a standard GSM call setup procedure by transmitting a setup signal to the wireless communication device, such as a mobile phone, preferably through a BSC and BTS.

0057The wireless communication device and the end terminal are both alerted at step <b>4</b>.<b>4</b>. In one embodiment, the mobile phone generates an alerting sound and sends an alerting signal to VMSC. The VMSC sends the alerting signal to the H.323 terminal and triggers the H.323 terminal to alert. The end terminal and the wireless communication device are then connected through the VMSC at step <b>4</b>.<b>6</b>. As an example of the connecting procedure, the user of a mobile phone picks up this particular calling request and the mobile phone sends a connecting signal to the VMSC. Upon receiving the connecting signal, the VMSC transmits a Q.931 connecting signal to the H.323 terminal. Finally, voice communications for the wireless communication device are activated by the VMSC at step <b>4</b>.<b>7</b>. In one embodiment, the VMSC initiates a voice-communicating PDP context for the wireless communication device upon receiving the connecting signal in order to provide voice communications. The users of the mobile phone and the H.323 terminal are able to proceed with their conversation through the communication of the VMSC, as illustrated in <figref idref="DRAWINGS">FIG. 8</figref>.

0058The systems and methods of the present invention provide VoIP service for radio networks by a VMSC that communicates between a circuit-switched network and a packet-switched network. The VMSC transforms between voice signals from and to a circuit-switched network and voice packets to and from a packet-switched network. Therefore, in one embodiment of the present invention, the systems and methods may operate under the standard H.323, GPRS, and GSM protocols without modifying the operation of traditional packet-switched GPRS and H.323 networks. In this particular embodiment, standard GSM and GPRS mobile phones without H.323 communicating capabilities, are able to receive VoIP service by implementing the systems or methods of the present invention.

0059It will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed systems and methods without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.